The drug discovery process is currently undergoing a fundamental revolution as it embraces “functional genomics,” that is, high throughput genome- or gene-based biology. This approach as a means to identify genes and gene products as therapeutic targets is rapidly superceding earlier approaches based on “positional cloning.” A phenotype, such as a biological function or genetic disease, would be identified and this would then be tracked back to the responsible gene, based on its genetic map position.
Functional genomics relies heavily on high-throughput DNA sequencing technologies and various tools of bioinformatics to identify gene sequences of potential interest from the many molecular biology databases now available. There is a continuing need to identify and characterize further genes and their related polypeptides/proteins, as targets for drug discovery.
Among the polypeptides of interest in drug discovery there are metalloproteases and other structurally and functionally related enzymes. Several diseases have been identified where metalloproteases play a critical role in the pathology of the disease. For example, a number of zinc metalloproteases or other structurally and functionally related enzymes have been identified and characterized in the state of the art, and it has become apparent that the participation of these enzymes, e.g. zinc metalloproteases, plays a role in a diverse array of biological functions encompassing both normal and disease situations. Zinc metalloproteases are subset of such enzymes whose catalytic functions are critically dependent on the zinc ion at the active site. This group of enzymes, which comprises various families classified on the basis of both sequence and structural information, are for example described to be intimately involved in such processes as embryonic development, cartilage and bone formation, processing of peptide hormones, reproduction, cardiovascular diseases, arthritis and cancer. Already active site-directed inhibitors of some of the zinc metalloproteases are being used therapeutically as e.g. antihypertensives.
On the basis of sequence and structural information around the zinc binding site of the zinc metalloproteases these enzymes may be classified into several families which may be further classified into superfamilies such as the “metzincins” (astacin, serratia, reprolysin, matrixin), the “gluzincins” (thermolysin, neprilysin, angiotensin converting enzyme, aminopeptidase), or the “zincins” comprising the superfamilies of metzincins and gluzincins. Such grouping not only aids in the elucidation of common catalytic and biosynthetic processing mechanisms, but also is invaluable in elucidating the function(s) of newly identified proteins which possess similar zinc binding motifs. Some individual examples of metalloproteases, e.g. zinc enzymes, already identified in the state of the art comprise neprilysin (NEP), endothelin converting enzyme (ECE), angiotensin converting enzyme, thermolysin, aminopeptidase, astacin, serratia, reprolysin, matrixin, insulinase, carboxypeptidase and DD-carboxypeptidase. The neprilysin family in particular comprises NEP, ECE-1, ECE-2, PEX, KELL, XCE/DINE and SEP/NEPII, the latter representing the metalloprotease of the present invention.
Diverse vasoactive peptides are known to represent substrates of some enzymes belonging to the neprilysin family, e.g. ANP, bradykinin, big ET-1, ET-1, substance P and angiotensin I, all represent substrates of NEP and/or ECE-1, and also of SEP.
From the above evidence based on the state of the art it is apparent that metalloproteases and other structurally and functionally related enzymes play key roles in health and disease. Thus there is a continued need to further uncover important functions and potential therapeutic applications for this group of enzymes and to provide novel metalloproteases with the subsequent development of novel synthetic stimulators (activators) or inhibitors, which can help provide new treatments for a variety of diseases of socio-economic importance.